1. Field of the Invention:
The invention relates to a high-efficiency water heater dip tube. The invention also relates to a method for reducing turbulence in water heaters.
Water heater efficiency is impaired by the premature commingling or admixing of already heated water with the inflowing or incoming cold water. A truly efficient water heater could give up its entire caloric content with little reduction in outlet temperature by preventing the already heated water from admixing with the incoming cold water.
Preserving the separation and natural stratification or layering of heat content in water heaters is highly desirable and should be accomplished by the dip tube in bringing the cold inflowing water down to the bottom of the heating chamber while avoiding its mixing with the layers of hot water in the upper tank. Although the typical dip tube does pass to the bottom of the tank, the problem is that the cold inflowing water discharges from the bottom facing dip tube with a directed stream of high velocity liquid in a laminar flowing column, similar to a fire hose. The cold water immediately reflects away from the adjacent bottom wall with significant turbulence and admixes with the entire tank. Horizontal or curved dip tubes with unrestricted outflow create a revolving cyclone of turbulence, which ultimately may be worse than the bottom facing tube. Some dip tubes are made so short that they create a tumbling turbulence of direct convection mixing well within the mid and upper tank which is equal to removing or having no dip tube installed.
2. Description of the Related Art:
U.S. Pat. No. 6,138,614 to Shropshire discloses an inlet tube with a plurality of upper openings near the top of the tube, as is described in column 1, lines 39-40. The bottom opening causes water flowing out of the tube to agitate sediment deposits at the bottom of the tank, as is described in column 2, lines 1-2. The tube 28 has two upper openings 34, 38 therein near the top of the inlet tube 28, as is described in column 3 lines 21-22. The upper openings 34, 38 are circular, as is described in column 3 line 36. A combined upper surface area is approximately 0.0140 square inches, as is described in column 3 lines 41-42. The inlet tube 28 also includes four lower openings 42 facing outwardly, and arranged at 90 degree increments. The lower openings are circular, as is described in column 3, lines 51-53. The inlet tube has a bottom opening 46 at its bottom end that opens downwardly, as is described in column 4 lines 4-5. Water is forced out of the bottom opening 46, stirring up sediment deposits on the bottom wall 20 of the storage tank 18, and thereby helping to resist sediment buildup, as is described in column 4, lines 54-57. Water will stream out of the upper opening when the appropriate pressure is attained in the tube 28. The cold water exiting through the upper opening 34, 38 mixes with the hottest water in the storage tank 18, thereby cooling the hottest water and maintaining it below a selected temperature, as is described in column 4, lines 62-67.
U.S. Pat. No. 5,365,891 to Hanning uses a dip tube turbulator to facilitate the dislodgement of sediment from the lower tank wall, and therefore the primary purpose is sediment control.
U.S. Pat. No. 4,898,150 to Lewis reveals a dip tube sediment turbulator for balanced pressure water flow to all sides of the end piece, thereby eliminating directional torque on the dip tube itself, and thus the primary purpose is sediment control as well.
U.S. Pat. No. 2,123,809 to Seitz uses a deflector at the bottom of the dip tube, so that the incoming water is directed downward against the bottom of the boiler and the water at that point is agitated so as to stir up rust and other sediment therein. Therefore, the primary purpose is also sediment control.
U.S. Pat. No. 3,762,395 to Taylor provides means on the inner end of the cold water inlet for directing a jet of water issuing therefrom tangentially with respect to the vertical axis of the tank to prevent a build up of sediment on the bottom of the tank. The primary purpose in Taylor is sediment control.
U.S. Pat. No. 4,898,124 to Granberg presents not a top mounted, vertically oriented dip tube, but a scale agitator for tank type liquid heaters employing a flexible, non-cathodic tube through which liquid can flow”. The primary purpose is once again sediment control.
U.S. Pat. No. 6,267,085 to Alphs presents not a top mounted, vertically oriented dip tube, but a cold water inlet bushing which screws into a threaded boss in the side wall of the hot water tank near the bottom. The Alphas device, which is not a dip tube, is for sediment control.
U.S. Pat. No. 4,505,231 to Syler teaches that a second curved plane has a plurality of openings in the underside thereof through which streams of water will be directed in the tank each time water is drawn out of the top of the tank. The streams of water serve to agitate the water in the bottom of the tank to prevent an accumulation of sediment therein. Once again, the device is not a dip tube and is intended for sediment control.
U.S. Pat. No. 6,935,280 to Scott shows a horizontal water inlet in the bottom of a water tank, with water flow deflectors to direct the water flow away from the flue and toward the side wall and bottom of the tank, thereby reducing an accumulation of scale. The device is again not a dip tube and is for sediment control.
U.S. Pat. No. 2,766,200 to Kaufman displays a bottom mounted water inlet, a baffle which is readily insertable into or removable from the tank after assembly, thereby facilitating coating of the inner surface of the tank, a protective anode for counteracting the electrolytic currents and a baffle connected to an influent pipe to provide stratification of the incoming water. The baffle is formed and disposed in such a way that it minimizes a “shadow effect” adjacent the influent pipe connection. The Kaufman device is not a dip tube, is used for electrolysis control and is not compatible with present systems.
U.S. Pat. No. 3,465,123 to Harris reveals a main function and purpose which is to direct and supply the incoming cold water from the city supply or other source so that it is concentrated within the vicinity of control means and is so focused and disposed that the discharged water plays on the control means and the heating element is caused to come on as soon as the hot water in the upper portion of the tank is drawn off for usage. The primary use is in controlling the thermostat and the dip tube is not of uniform diameter and is therefore not constructed for easy insertion or replacement after manufacture.
U.S. Pat. No. 4,964,394 to Threatt teaches a modified dip tube with a heat trap disposed therein. Threatt does not disclose a dip tube but instead a combined device which still enables strong laminar flow admixture.
U.S. Pat. No. 6,553,947 to Bradenbaugh shows means for improved mixing of cold water supply with water stored in the water tank of a water heater and means for limiting surges of water into and out of a water tank. The multipart system uses accessory water inlet and outlet regulators, a mid level tank baffle and intentionally augments premixing heated and unheated water at several levels, which defeats the purpose of having a dip tube.
U.S. Pat. No. 5,988,117 to Lannes presents an inlet which includes means for deflecting the water flow through openings in the inlet's wall in order to reduce the generation of temperature gradients that otherwise tend to develop within water heater tanks. Increased premixing defeats the purpose of the dip tube and reducing the temperature gradients worsens efficiency.
All of the prior art dip tubes inadvertently cause the very condition they were intended to prevent.